<!doctype html>
<html lang="en">
 <head>
  <meta charset="UTF-8">
  <meta name="Generator" content="EditPlus®">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">
  <title>Document</title>
 </head>
 <body>
  <script>
	 var a =parseInt(prompt('请输入年份',''));
	 if (0 == a%100)
	 {
		 if (0 == a%400)
		 {
			 alert('1今年是闰年');
		 }else{
			 alert('1今年不是闰年');
		 };
	 }else if (0 != a%100 && a>0)
	 {
			if (0 == a%4)
			{
				alert('2今年是闰年');
			}else{
				 alert('2今年不是闰年');
			};
	 }else{
			alert('输入错误，请从新输入');
	 };

 </script>
 </body>
</html>
